Method and system for distributed admission control in mobile ad hoc networks (manets)

ABSTRACT

Techniques are provided for distributed admission control (AC) in a mobile ad hoc network (MANET). When the source node transmits a new communication stream (NCS) toward a destination node, other nodes allow transmission of the NCS during a temporary admission period even though the NCS has not yet been admitted. The nodes can determine whether the NCS causes degradation of any existing communication stream(s) (ECSs) supported by that node based on existing QoS requirements associated with the ECSs. In some implementations, nodes which determine that they are unable to support ECSs transmit an indicator which notifies other nodes that admission of the NCS is denied by that node. By contrast, if none of the nodes transmit an indicator during the temporary admission period, then the NCS is “admitted” to the MANET and the source node is permitted to keep transmitting the NCS, a variation thereof or another new communication stream.

FIELD OF THE INVENTION

The present invention relates generally to wireless communications andmore particularly to admission control techniques in a mobile ad hocnetwork.

BACKGROUND

Types of wireless networks include infrastructure-based wirelessnetworks and ad hoc wireless networks.

Ad hoc networks are self-forming networks which can operate in theabsence of any fixed infrastructure, and in some cases the ad hocnetwork is formed entirely of mobile nodes. A mobile ad hoc network(MANET) typically includes a number of geographically-distributed,potentially mobile units, sometimes referred to as “nodes,” which arewirelessly connected to each other by one or more links (e.g., radiofrequency communication channels). The nodes can communicate with eachother over a wireless media without the support of aninfrastructure-based or wired network. Links or connections betweenthese nodes can change dynamically in an arbitrary manner as existingnodes move within the ad hoc network, as new nodes join or enter the adhoc network, or as existing nodes leave or exit the ad hoc network.Because the topology of an ad hoc network can change significantly,techniques are needed which can allow the ad hoc network to dynamicallyadjust to these changes. Due to the lack of a central controller, manynetwork-controlling functions can be distributed among the nodes suchthat the nodes can self-organize and reconfigure in response to topologychanges.

One characteristic of ad hoc network nodes is that each node candirectly communicate over a short range with nodes which are a single“hop” away. Such nodes are sometimes referred to as “neighbor nodes.”When a node transmits packets to a destination node and the nodes areseparated by more than one hop (e.g., the distance between two nodesexceeds the radio transmission range of the nodes, or a physical barrieris present between the nodes), the packets can be relayed viaintermediate relay nodes (“multi-hopping”) along a route until thepackets reach the destination node. In such situations, eachintermediate relay node routes the packets (e.g., data and controlinformation) to the next node along the route, until the packets reachtheir final destination. For relaying packets to the next node, eachnode maintains routing information collected through communications withits neighboring nodes. The routing information can also be periodicallybroadcast in the network to reflect the current network topology.Alternatively, to reduce the amount of information transmitted formaintaining accurate routing information, the network nodes may exchangerouting information only when it is needed. In many multi-hop ad hocnetworks, multiple routes can be present between a source node and adestination node for communication of a particular data stream or“flow.”

Ad hoc networks can generally be categorized into two different systemarchitectures which support different control and/or resource allocationprotocols. In distributed ad hoc network architectures, each node sharesthe entire spectrum with other nodes, and each node acts independentlyin selection of resources (e.g., frequency, time or code allocations).By contrast, in cluster ad hoc network architectures, a clusterhead nodeacts as a centralized point of control and manages resource allocation,control, and management functions for a cluster of proximate nodessomewhat like a base station in conventional cellular networks. Amongother functions, the clusterhead node can direct control information anddata traffic to appropriate nodes in the network. Adjacent clustersshare resources, such as, time, frequency, or code allocations. Theclusterhead node allocates resources among proximate nodes (associatedwith the clusterhead node) in its cluster based on service requests fromthe proximate nodes.

Quality-Of-Service (QoS) is becoming an increasingly important issue inmany types of MANETs. QoS generally refers to control mechanisms toensure that connections are able to meet their minimum communicationrequirements, such as time to provide service, voice quality, minimumdata throughput, maximum end-to-end delay, echo, packet loss,reliability and so on. QoS can provide different priority to differentusers or data flows, or guarantee a certain level of performance to adata flow in accordance with requests from an application program or theinternet service provider policy. QoS guarantees are importantespecially for real-time streaming multimedia applications, for examplevoice-over-IP (VoIP) and IP-TV, since these types of applications oftenrequire fixed bit rates and are delay sensitive, and QoS guarantees mustbe provided even as the MANET becomes congested.

One “building block” required to implement QoS is commonly referred toas “admission control.” Admission control techniques control admissionor entrance of new, inelastic communication streams or “traffic” into aMANET. Admission control can be employed whenever a system has finitecapacity. The basic principle of admission control is that a newcommunication stream should only be “admitted” in the system if it doesnot cause the system to operate above its maximum capacity level;otherwise, the new communication stream should be denied access to thesystem. If admission control techniques are not implemented and a newcommunication stream is admitted causing the system to operate above itscapacity level, one or more of the existing connections may no longer beable to support Quality-of-Service (QoS) requirements of the particulardata stream.

It is desirable to apply admission control procedures in MANETs suchthat a new communication stream be permitted to enter the MANET (or be“admitted” to the MANET) only if the existing communication streams areable to maintain their QoS requirements. However, in a MANET, it isdifficult to accurately determine the capacity of a particularcommunication scenario or topology due to the lack of central controllerand due to the lack of knowledge of interference conditions in theMANET. Therefore, it is difficult for nodes to individually determinewhether a new communication stream will cause one or more existingcommunication streams to no longer support its QoS requirements. It isdesirable that nodes cooperate to perform admission control functions ina distributed manner.

Given that the capacity of a MANET depends on its topology, if acommunication stream is denied access to the system, it may retry accessthrough a different route, which may not cause degradation in the QoS ofexisting communication streams. In other words, upper layers interpret adenial decision as a signal to try alternative routes.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separate viewsand which together with the detailed description below are incorporatedin and form part of the specification, serve to further illustratevarious embodiments and to explain various principles and advantages allin accordance with the present invention.

FIG. 1 is a block diagram of a mobile ad hoc network (MANET);

FIG. 2 is a flowchart showing a method for distributed admission control(AC) in the MANET in accordance with some embodiments of the invention;and

FIG. 3 is a flowchart showing a method for distributed admission control(AC) in the MANET in accordance with some implementations of theinvention; and

FIG. 4 is a flowchart showing one example of a method for determiningwhether a new communication stream (NEW) is to be admitted or denied inaccordance with some implementations of the invention.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and are not drawn to scale.

DETAILED DESCRIPTION

Before describing in detail embodiments that are in accordance with thepresent invention, it should be observed that the embodiments resideprimarily in combinations of method steps and apparatus componentsrelated to distributed admission control techniques in a mobile ad hocnetwork. Accordingly, the apparatus components and method steps havebeen represented where appropriate by conventional symbols in thedrawings, showing only those specific details that are pertinent tounderstanding the embodiments of the present invention so as not toobscure the disclosure with details that will be readily apparent tothose of ordinary skill in the art having the benefit of the descriptionherein.

In this document, relational terms such as first and second, and thelike may be used solely to distinguish one entity or action from anotherentity or action without necessarily requiring or implying any actualsuch relationship or order between such entities or actions. The terms“comprises,” “comprising,” or any other variation thereof, are intendedto cover a non-exclusive inclusion, such that a process, method,article, or apparatus that comprises a list of elements does not includeonly those elements but may include other elements not expressly listedor inherent to such process, method, article, or apparatus. An elementproceeded by “comprises . . . a” does not, without more constraints,preclude the existence of additional identical elements in the process,method, article, or apparatus that comprises the element.

It will be appreciated that embodiments of the invention describedherein may be comprised of one or more conventional processors andunique stored program instructions that control the one or moreprocessors to implement, in conjunction with certain non-processorcircuits, some, most, or all of the functions for distributed admissioncontrol techniques in a mobile ad hoc network. The non-processorcircuits may include, but are not limited to, a radio receiver, a radiotransmitter, signal drivers, clock circuits, power source circuits, anduser input devices. As such, these functions may be interpreted as stepsof a method for distributed admission control in a mobile ad hocnetwork. Alternatively, some or all functions could be implemented by astate machine that has no stored program instructions, or in one or moreapplication specific integrated circuits (ASICs), in which each functionor some combinations of certain of the functions are implemented ascustom logic. Of course, a combination of the two approaches could beused. Thus, methods and means for these functions have been describedherein. Further, it is expected that one of ordinary skill,notwithstanding possibly significant effort and many design choicesmotivated by, for example, available time, current technology, andeconomic considerations, when guided by the concepts and principlesdisclosed herein will be readily designed to allow generating suchsoftware instructions and programs and ICs with minimal experimentation.

Any embodiment described herein is not necessarily to be construed aspreferred or advantageous over other embodiments. All of the embodimentsdescribed in this Detailed Description are illustrative and aredescribed to enable persons skilled in the art to make or use theinvention and not to limit the scope of the invention which is definedby the claims.

Terminology

In this document, the terms “communication stream,” “communicationsession,” and “communication flow” can be used interchangeably. As usedherein, the term “communication stream” refers to a communicationsession or data stream which flows between a source node and adestination node. The communication stream often requires a particular,guaranteed Quality of Service (QoS). In some cases, the communicationstream passes “through” one or more intermediate relay nodes locatedbetween the source node and the destination node.

As used herein, the term “Quality of Service (QoS)” refers to one ormore requirements of a particular communication stream or “flow” that istransmitted between a source node and a destination node. Theserequirements can include, for example, data rate requirements, bandwidthrequirements, delay requirements, jitter requirements, maximum packetloss requirements, etc. The QoS requirements may be specified, forexample, using at least one of a plurality of fields for thecommunication stream including, but not limited to, a bandwidth requestfield, a maximum or minimum data rate field, a maximum or minimum delayfield, a jitter field, a maximum packet loss field and a total delayincurred field. For example, the minimum data rate is the data ratewhich needs to be maintained at all the intermediate nodes to satisfythe QoS requirement of this particular data stream. The maximum delay isthe maximum delay which packets of a data stream can sustain whiletraversing along the route while still maintaining the QoS requirement.

As used herein, the term “support,” as used in the phrases “node whichsupports,” “node supports . . . communication stream,” “supportcommunication stream,” “node supports a communication stream” “nodesupporting a communication stream” and other variations thereof, meanthat a node is participating in communication of a communication stream,and this can mean that a node is generating a communication stream(e.g., source node), transmitting a communication stream, receiving acommunication stream, relaying or retransmitting a communication stream(e.g., relay nodes), and/or processing a communication stream.

Overview of Admission Control

Admission control procedures are used to control the entrance of newcommunication sessions or streams into a network such that existingcommunication sessions or streams are not compromised. In other words,given a set of existing communication sessions or streams, admissioncontrol procedures avoid the entrance of a new communication sessionthat can cause QoS degradation to any of the existing communicationsessions. Admission control procedures are usually applied to sessionsor streams that are forecasted to last for a relatively long time andthat have clear traffic characteristics. Two-way voice communicationsessions and other ‘inelastic’ traffic flows are example of sessions towhich admission control procedures apply. Such sessions have thecharacteristic that they either exist with a certain fixed andpre-determined level of data throughput (and other QoS metrics) or theycan not exist. To implement admission control procedures in a MANET, avariety of issues can arise which are not a concern in other types ofnetworks.

In MANETs the communication channel is shared among nodes, whereas inthe Internet, for example, routers have dedicated physical links betweeneach other; i.e., when one router decides to transmit to another router,it simply accesses the physical cable that is dedicated for itscommunication, without any contention. In Ethernet networks a physicalchannel is shared among nodes of the network. However, in MANETs radiochannels are used by nodes. As such, the carrier-sense multiple access(CSMA) procedures used in Ethernet can operate much more efficientlythan in CSMA-based MANETs since an Ethernet transmission can be sensedby all nodes of the Ethernet network. In MANETs, the characteristics ofradio transmission and the need for channel reuse causes the hidden andexposed node problems. For these reasons, it is important to considerspecific Admission Control procedures for MANETs.

Another issue is the lack of central control. The lack of centralcoordination or control forces the admission control procedures to be“distributed” among nodes in the MANET. This is true in both autonomousMANETs and locally-centralized “cluster-based” MANETs. The distributedentities (nodes or cluster-head nodes) that make admission decisionshave limited information about the resource utilization of neighboringnodes. Erroneous admission decisions can result, for example, because nosingle entity has all the information regarding other ongoingcommunication streams, and further because multiple entities areinvolved in making admission decisions based on limited information.Exchanging information among decision making nodes can help alleviatethis problem; however, this undesirably increases control overhead inthe network.

Another such issue relates to the difficulty in determining the currentstate of existing communication streams being communicated in the MANET,and whether the existing communication streams of the MANET are able tosustain the QoS requirements of those streams. For example, even ifinformation needed to make an admission decision is concentrated at asingle node, making the admission decision (i.e., whether a givencommunication stream can be successfully admitted given QoS requirementsof existing communication streams) is a computationally intense process,requiring, for example, use of constrained optimization processing.

Overview of Distributed Admission Control (AC) Techniques

In accordance with some embodiments of the present invention, techniquesare provided for distributed admission control (AC) in a mobile ad hocnetwork (MANET) which includes a plurality of nodes including, forexample, a source node, a destination node, and a plurality of firstnodes each supporting at least one existing communication stream whichhas one or more existing QoS requirements associated therewith. When thesource node transmits a new communication stream toward the destinationnode along a first route, other nodes which receive the newcommunication stream allow transmission of the new communication streamduring a temporary admission period even though the new communicationstream has not yet been admitted. Each of the nodes which receive thenew communication stream during the temporary admission period candetermine whether the new communication stream causes degradation of anyexisting communication stream(s) supported by that node based onexisting QoS requirements associated with the existing communicationstream(s). If any nodes determine that they are unable to supportexisting QoS requirements of existing communication stream(s), thenthose nodes can then transmit an indicator which indicates that the newcommunication stream causes degradation of one or more existing QoSrequirements associated with the existing communication stream(s)supported by that node. This indicator serves to notify other nodes thatadmission of the new communication stream is denied by that node. Bycontrast, if none of the nodes determine that the new communicationstream causes degradation of existing communication streams supported bythose nodes, then after the temporary admission period, the newcommunication stream is “admitted” and the source node is permitted tokeep transmitting the new communication stream or a variation thereof.

Example embodiments will now be described below with reference to FIGS.2 through 4 after a brief description of an example mobile ad hocnetwork (MANET). FIG. 1 is a block diagram of a mobile ad hoc network(MANET) including a plurality of nodes 112, 114, 116, 118, 120, 122,124, 126, 128, 130, 132, 134, 136, 138, 140 and the topologicalcommunication spacings between those nodes 112-140. As illustrated inFIG. 1, at least some of the nodes 114, 116, 118, 120, 124, 126, 128,130, 134, 136, 138, 140 are actively communicating with other nodes asrepresented by lines or communication links which connect particularones of the nodes, and other nodes 112, 132 are not activelycommunicating with other nodes and therefore have no lines orcommunication links connecting those nodes 112, 132 to other nodes. InFIG. 1, any node 112-140 is presumed to be one hop away (e.g., withindirect communication range of) from another horizontally adjacent nodeor another vertically adjacent node, and more than one hop away (e.g.,outside direct communication range of) any diagonally located nodes. Forinstance, node A 112 is one hop away from node B 114 and node F 122, butis more than one hop away from source node 124. Moreover, although theexample topology in FIG. 1 illustrates that all nodes are spaced apartfrom one another in a “grid,” this topology is for illustrative purposesonly and is not intended to imply that the nodes are physically spacedfrom each other in this manner, but instead merely implies that any node112-140 is presumed to be within direct communication range of or “onehop away from” any other horizontally adjacent node or any anothervertically adjacent node. In many real scenarios, the nodes arearbitrarily spaced apart with respect to one another by differentphysical distances, and the relative physical spacing between nodeschanges arbitrarily as nodes 112-140 move about. For example, althoughFIG. 1 illustrates node A 112 and node K 132 as being equidistantlyspaced apart with respect to node F 122, however, the illustratedtopology merely implies that node A 112 and node K 132 are onecommunication hop away from node F 122 at this particular instant.

In general, the nodes can be classified as either a source node of aparticular communication stream, a destination node of the particularcommunication stream, an intermediate relay node which relays theparticular communication stream towards the destination node, or aperipheral node not actively involved in communicating the particularcommunication stream. In addition, any node can simultaneously functionas a source node, a destination node, a relay node and/or a peripheralnode with respect to different communication streams. For example,source node 124 serves as a source node with respect to newcommunication stream (NEW), serves as a relay node which supports twoexisting communication streams 2, 3 which flow through it, and is aperipheral node with respect to communication streams 1, 4. With respectto the existing communication streams 1-4, node D 118 sourcescommunication stream 1 to node O 140 (destination) through node E 120and node J 130. Node B 114 sources communication stream 2 to node J 130(destination) through source node 124, relay node 1 126 and relay node 2128. Node F 122 sources communication stream 3 to node L 134(destination) through source node 124. Node C 116 sources communicationstream 4 to node M 136 (destination) through relay node 1 126. As such,nodes 120, 124, 126, 128, 130 serve as relay nodes, where node E 120 andnode J 130 each support existing communication stream 1 which flowsthrough it; source node 124 supports two existing communication streams2, 3 which flow through it; relay node 1 126 supports two existingcommunication streams 2, 4 which flow through it; and relay node 2 128supports one existing communication stream 2 which flows through it.

The nodes illustrated in FIG. 1 perform different functions depending ontheir relative roles with respect to a given communication. For example,a node can be an end node (i.e., source node or destination node) of anew communication stream (NEW) seeking admission, an intermediate relaynode of the new communication stream (NEW), an end node of existingcommunication stream 1-4, a relay node of an existing communicationstream 1-4 or a peripheral node. In the scenario illustrated in FIG. 1,there is one new communication stream (NEW) which seeks admission forcommunication through the MANET 100, and there are four existingcommunication streams 1-4. The new communication stream (NEW) isillustrated in FIG. 1 with a dashed-line labeled since it is not yetadmitted and seeks “permission” or “authorization” from other nodes toflow from source node 124 to the destination node 138 via acommunication path or “route” which includes communication links withrelay node 1 126 and relay node 2 128.

Depending on the particular radio and interference conditions of othernodes in the network, the new communication flow between nodes 124, 138,if admitted, may cause degradation of one or more of the existingcommunication streams 1-4 such that quality of service (QoS)requirements of one or more of the existing communication streams areviolated. To address such issues, distributed admission controltechniques for MANETs will now be described below with reference to FIG.2 and FIGS. 3 and 4.

FIG. 2 is a flowchart showing a method for distributed admission control(AC) 200 in the MANET in accordance with some embodiments of theinvention.

The method 200 for distributed admission control (AC) begins at step205, and at step 210, the source node 124 transmits a new communicationstream (NEW) toward the destination node 138 along a first route whichincludes relay nodes 126, 128. Upon receiving (or detecting the presenceof) the new communication stream during a temporary admission period,other nodes which receive (or detect the presence of) the newcommunication stream (NEW) will “allow” or “permit” transmission of thenew communication stream (NEW) at step 220 even though the newcommunication stream has not yet been admitted. For example, node J 130does not “receive” the new communication stream (NEW), but it may stillbe able to detect the presence of the new communication stream (NEW),and therefore node J 130 will allow or permit continued transmission ofthe new communication stream (NEW) during the temporary admissionperiod.

At step 230, each node which receives the new communication streamduring the temporary admission period can determine whether its existingcommunication stream(s) would still be supported (per QoS requirementsof those existing communication stream(s)) if the new communicationstream (NEW) is admitted. In one implementation, if the newcommunication stream causes degradation of any existing communicationstream(s) supported by that node as determined based on existing QoSrequirements associated with the existing communication stream(s), thenthe decision at block 230 would be “NO.”

If none of the nodes determine that the existing communication stream(s)it supports would be degraded (per QoS requirements of those existingcommunication stream(s)) if the new communication stream (NEW) isadmitted, then after the temporary admission period, the newcommunication stream is “admitted” at step 235 and the source node ispermitted to keep transmitting the new communication stream or avariation thereof. In other words, when a node determines that the nodecan adequately support QoS requirements of its existing communicationstreams, a new or continued transmission of the new communication stream(NEW) by the source node will be permitted. Here, a “new or continuedtransmission” of the new communication stream (NEW) can refer to: acontinuation of the current, new communication stream; a new version ofthe current, new communication stream (i.e., starting at the beginning);or another communication stream different than the current, newcommunication stream.

By contrast, if any nodes determine that they are unable to supportexisting QoS requirements of their existing communication stream(s),then those nodes can then transmit an infringement indicator at step240. The infringement indicator indicates that the new communicationstream causes degradation of one or more existing QoS requirementsassociated with the existing communication stream(s) supported by thatnode, and serves to notify other nodes that admission of the newcommunication stream is denied. At step 250, at least some of the nodesreceive the infringement indicator, and at step 260, those nodes stopprocessing packets of the new communication stream so that the newcommunication stream is “denied” admission.

FIG. 3 is a flowchart showing a method 300 for distributed admissioncontrol (AC) in the MANET in accordance with some implementations of theinvention. To illustrate how the method 300 for distributed admissioncontrol (AC) can be applied to one example network configuration where anew communication stream (NEW) seeks to be admitted, method 300 will bedescribed below with reference to the mobile ad hoc network (MANET) 100illustrated in FIG. 1; however, it will be appreciated that method 300could be applied in the context of any MANET configuration. As describedabove, the MANET 100 of FIG. 1 comprising a plurality of nodes includinginactive nodes 112, 132 (i.e., nodes not supporting or participating incommunication of any communication stream), a source node 124, adestination node 138, relay nodes 126, 128 along the route between thesource node 124 and the destination node 138, and a plurality ofperipheral nodes 114, 116, 118, 120, 122, 130, 134, 136, 140. Each ofperipheral nodes 114, 116, 118, 120, 122, 130, 134, 136, 140 “support”(or are participating in communication of) at least one existingcommunication stream 1-4 which has one or more existing QoS requirementsassociated therewith, but do not support communication of a newcommunication stream (NEW) which seeks to be communicated between thesource node 124 and the destination node 138. In the description below,the peripheral nodes 114, 116, 118, 120, 122, 130, 134, 136, 140 arealso referred to as “first” nodes 114, 116, 118, 120, 122, 130, 134,136, 140 for simplicity.

The method 300 for distributed admission control (AC) starts at step305, and at step 310 the source node 124 begins to transmit a newcommunication stream (NEW) having particular QoS requirements associatedtherewith (e.g., VoIP flow that requires guaranteed service) toward thedestination node 138 along a route between the source node 124 and thedestination node 138. As will be appreciated by those skilled in theart, one or more intermediate relay nodes 126, 128 can be present alongthe route between the source node 124 and the destination node 138. Insuch scenarios, the new communication stream is communicated to thedestination node “via at least one relay node.” For instance, in theexample illustrated in FIG. 1, the new communication stream (NEW) iscommunicated from the source node 124 towards the destination node 138by any intermediate relay nodes 126, 128. In other scenarios (notillustrated in FIG. 1), in which no intermediate nodes are presentbetween the source node 124 and the destination node 138, method 300still works even when the route does not include any intermediate relaynodes (i.e., when the source node is a one-hop neighbor of thedestination node 138).

Depending on the implementation, the new communication stream (NEW) canbe either an actual communication stream transmitted from the sourcenode 124 (and destined for destination node 138) or can be a new “test”or “dummy” communication stream. In one exemplary implementation, thesource node 124 can transmit dummy packets at the same rate at which itwould transmit actual packets of the new communication stream (NEW)(e.g., dummy packets are transmitted at the same rate as the actual newcommunication stream (NEW) would consume). In some implementations, thedummy packets are of a same packet size and a same packet interarrivaltime of regular packets which are transmitted as part of the newcommunication stream (NEW). The transmission of dummy packets may bepreferred in implementations in which the communication between thesource and destination nodes should only be allowed to begin after ithas been confirmed that the new communication stream can be admitted.For example, in VoIP applications, it may be undesirable to allow thevoice communication to start and interrupt it moments later if thecommunication stream is denied.

During initial transmission of the new communication stream (NEW), ithas not yet been “admitted,” however, at step 320, each of the nodes112-140 (including source, destination, relay nodes (if any), andperipheral nodes (if any)) allow transmission of the new communicationstream (NEW) to temporarily flow for a temporary admission period. Whenprocessing packets of the new communication stream (NEW), the recipientnode can determine whether the temporary admission period has expired.The temporary admission period can be a pre-determined period orvariable depending on network conditions, and represents the amount timeduring which the new communication stream (NEW) is temporarily admittedor permitted to flow without being actually admitted. After thetemporary admission period, assuming no nodes object to admission of thenew communication stream by transmitting an indicator, the newcommunication stream is “admitted” and the source node 124 can starttransmitting actual traffic packets of the new communication stream(NEW). There are numerous ways by which a node can determine whether ornot a particular communication stream is still within its temporaryadmission period, as will be described below at step 344.

At step 330, each of the nodes 112-140 which receive the newcommunication stream (NEW) determine, during the temporary admissionperiod, whether the new communication stream (NEW) causes degradation ofany existing communication streams 1-4 supported by and/or flowingthrough that node based on existing QoS requirements associated with theexisting communication streams 1-4. In this regard, the “existing”communication streams can be any communication streams the node isinvolved in communicating, including for example, communication streamsflowing through the particular node, generated by the particular node,destined to the particular node, processed by the particular node, orrelayed by the particular node. In the implementation illustrated inFIG. 3, if the node determines that the new communication stream (NEW)does not cause degradation of any existing communication streams 1-4supported by and/or flowing through that node based on existing QoSrequirements associated with the existing communication streams 1-4,then method 300 proceeds to step 335 where the new communication stream(NEW) is admitted. There are multiple techniques for making thedetermination at step 330 and one embodiment will be described belowwith reference to FIG. 4.

At step 340, any node or node(s), that determine that the newcommunication stream (NEW) is to be denied admission (e.g., because thenew communication stream (NEW) causes degradation of any existingcommunication streams supported by that node), transmit an indicatorwhich indicates that the new communication stream (NEW) is to be deniedadmission. The indicator transmitted from a node at step 340 indicatesto other nodes that the network topology is currently unable to supportthe new communication stream (NEW) without disrupting existing QoSrequirements associated with one or more of the existing communicationstreams 1-4. This way any nodes “participating in communication of” thenew communication stream (NEW) (source node, destination node and anyintermediate relay nodes along the route between the source node and thedestination node) are likely to receive notice that the newcommunication stream (NEW) might disrupt one or more existingcommunication streams.

It should be appreciated that the term “indicator” is not to beinterpreted in a restrictive sense. Throughout the description the term“indicator” is used to describe a communication which includesinformation which indicates that the network topology is currentlyunable to support the new communication stream without disruptingexisting QoS requirements associated with any existing communicationstreams. The indicator comprises a reference to the new communicationstream (NEW) that is being denied admission, a transmitting nodeidentifier (ID), one or more metrics and, optionally, the IDs of othernodes that may have also transmitted the indicator in the recent past.In one implementation, each node which transmits an indicator caninclude a node ID of the node which initially generated the indicatorand a metric (C) whose value is a function of the ratio of time that thenode senses the channel as being busy and a number of indicatorsreceived from external communication streams. Nodes of the communicationstream being denied which relay the indicator towards the source node124 can also attach their values of the metric (C) to the indicator asthe indicator is being returned to the source node 124. In someimplementations, nodes of a temporarily admitted new communicationstream (NEW) can attach their current metrics (C) into fields of the“dummy” packets being transmitted during the temporary admission period.This provides information regarding the metrics (C) of all the nodes inthe route. In another implementation, the node transmitting an indicatorincludes a metric that indicates a lower QoS level in which the newcommunication stream being denied would have a higher chance of beingaccepted, allowing the source node the possibility of changing orretrying the new communication stream with a lower QoS level. Forexample, the indicator can include information which indicates whetherthe new communication stream (NEW) would have a better chance ofadmission if the overall QoS requirements of the new communicationstream (NEW) are changed or reduced to a lower QoS level (i.e., thelower QoS level would contain a lower effective data throughput orhigher end-to-end delay).

Depending on the implementation, the indicator can be transmitted in aunicast transmission, a multicast transmission, or a broadcasttransmission.

In some implementations, the indicator can be implemented as anindependent or “stand-alone” message called a QoS Infringement Alert(QIA) message. In other implementations, the indicator can implementedas part of a message such as a standard HELLO message, a beacon message,neighbor advertising message, routing advertising message, or link stateadvertising message, for example, as an information element or fieldthat can be included as part of another message. In still otherimplementations, the indicator can implemented as part of a data packetby using specific bits in a packet (e.g., in a header of a data packet,for example, by setting specific bits in a MAC header to indicate theQoS infringement condition).

In one implementation of step 340, when the node is not a relay node forany communication stream that is still in its temporary admission period(e.g., an end node of the new communication stream), then the node canbroadcast the indicator. Although not illustrated in FIG. 3, if QoSinfringement continues, this implementation of step 340 can be repeatedregularly or periodically with a period set high enough so that thenumber of indicators which are broadcast is not too large.

In one implementation of step 340, when a particular peripheral node114, 116, 118, 120, 122, 130, 134, 136, 140 which is not located alongthe route determines that the particular peripheral node is unable tosupport existing QoS requirements of one or more existing communicationstreams 1-4 and that the QoS of an existing communication stream 1-4which it supports is degraded by or as a result of the new communicationstream (NEW), the particular peripheral node broadcasts an indicator tonodes involved in communicating the new communication stream (NEW). Forexample, the existing communication stream 4 of FIG. 1 could suffer QoSdegradation and peripheral node 136 could generate and broadcast anindicator. In some implementations, in order to reduce the number ofindicators and reduce the control overhead caused by such indications,the node performs additional checks before deciding to broadcast (asopposed to unicast or multicast) the indicator. For example, in oneimplementation, the decision of whether to broadcast an indicator can bebased on the fraction of time that the channel is busy. In anotherimplementation, the node monitors transmissions of neighbor nodes,determines whether a packet transmission rate has increased by more thana particular percentage in at least one of its neighbor nodes, andbroadcasts the indicator only if packet transmission rate has increasedby more than a particular percentage in at least one of its neighbornodes. By monitoring the packet transmission rate of neighbor nodes, anode can determine whether (or not) to suppress the transmission of theindicator. When a node suppresses transmission of the indicator to thenodes which are proximate the source node, when an existing stream isdisrupted by another new communication stream that is near the node, theoverall control overhead associated with transmission, reception andprocessing of the indicator messages can be reduced.

In another implementation of step 340, when a particular node 112-140determines that the particular node is unable to support existing QoSrequirements of one or more existing communication streams 1-4 and thatthe QoS of an existing communication stream 1-4 which it supports isdegraded by or as a result of one or more new communication streams(NEW), the particular node transmits a unicast indicator to a neighbornode which has a highest increase of packet transmission rate during alast measurement period. By unicasting the transmission of theindication to a particular neighbor node, the transmitting node is ableto deny just a subset of the new communication streams.

In another implementation of step 340, a relay node which is locatedalong the route of the new communication stream (NEW) can transmit aunicast indicator towards the source node 124 when the particular relaynode determines that it is unable to support existing QoS requirementsof one or more existing communication streams 1-4 because of the newcommunication stream (NEW).

In another implementation of step 340, if an end node (source node 124or destination node 138) of a new communication stream (NEW) determinesthat the new communication stream (NEW) is causing QoS infringement ofan existing communication stream 1-4, the end node 124, 138 transmits anindicator which indicates the QoS infringement to all relay nodes 126,128 involved in communicating the new communication stream (NEW). In oneimplementation, the end node 124, 138 can do this by communicating aunicast indicator (e.g., a QoS Infringement Alert (QIA) message) whichreferences the new communication stream (NEW), and may also optionallyinclude a timer to avoid generating too many indicators. In anotherimplementation, the source node 124 can communicate the indicator usingspecific bit(s) in one or more packets of the new communication stream(NEW) (e.g., communicate specific bits in the MAC header of packets ofthe new communication stream (NEW)). In an implementation where specificbit(s) in the MAC header are used, such bits can be set in all packetsof the new communication stream (NEW) generated by the source node 124.

At step 342, one or more nodes receive the indicator, and at step 344determine whether the temporary admission period has expired. There arenumerous ways by which a node can determine whether or not a particularcommunication stream is still within its temporary admission period. Ingeneral, the nodes 112-140 can detect whether the new communicationstream (NEW) is in its temporary admission period by inspectinginformation in packets of the communication stream.

For example, in one implementation, each node tracks the time that eachcommunication stream has existed and compares it against a timethreshold to determine whether the communication stream is within thetemporary admission period.

In still another implementation, each node can determine a category ofthe last received packet for a particular communication stream, andthen, based on the category of the last received packet, determinewhether the communication stream is within the temporary admissionperiod. This approach beneficially reduces the amount of processing bynodes in determining whether a particular communication stream is stillwithin its temporary admission period. For instance, in oneimplementation, where the new communication stream is initially sentusing “dummy” or “test” packets, each node can determine if the lastpacket of the communication stream that the node received is a dummypacket, and, if so, determines that the communication stream is withinthe temporary admission period.

In yet another implementation, each node can determine if the lastpacket of the communication stream that the node received has a mark onits header (or even a mark on an IP header, like the TOS field)indicating that the flow is still temporary, and, if so, determines thatthe communication stream is within the temporary admission period.

In still another implementation, the source node 124 adds a value topackets of new communication stream (NEW) indicating the remainingduration of the temporary admission period. Recipient nodes can thencheck this value to determine whether the new communication stream (NEW)is still within the temporary admission period. For example, the sourcenode 124 adds a value to each packet (in a control field, for example)which indicates a duration until a temporary admission period for thenew communication stream (NEW) expires (i.e., time until time remaininguntil the new communication stream (NEW) becomes admitted), and then,based on the value, each node can determine whether the newcommunication stream (NEW) is still within the temporary admissionperiod. This implementation is particularly useful, for example, in ascenario where a node is processing or communicating multipletemporarily admitted communication streams, and decides to block justsome of them, since the node can use the remaining time information todecide which temporarily admitted communication streams to deny or block(e.g., the node could deny or block the most recent temporarily admittedcommunication stream).

If it is determined at step 344 that the temporary admission period hasexpired, then the method 300 proceeds to step 335 where the newcommunication stream (NEW) is admitted. If the temporary admissionperiod has not expired at step 344, then the method 300 proceeds to step350, where the method 300 proceeds based on the status (i.e., sourcenode or other node) of the receiving node with respect to the newcommunication stream (NEW) referenced by the indicator.

For example, when the node is any node other than the source node 124(e.g., any node which is not the source node such as relay nodes 126,128 or destination node 138), the method 300 proceeds to step 355 or 360depending on the implementation since step 355 is optional and is notpracticed in all implementations.

In implementations where step 355 takes place, the node determineswhether the new communication stream (NEW) has at least one metric whichis greater than a corresponding metric of an existing communicationsupported by the node. The metric is to be computed based on any of thefollowing parameters or combination of them: type of new communicationstream; organizational rank of user of source node; and organizationalrank of user of destination node. In essence, higher metric implies thatthe new communication stream is “better” or has a higher priority thanat least one of the existing communication streams.

If the new communication stream (NEW) has at least one metric which isgreater than a corresponding metric of an existing communicationsupported by the node, then the method 300 proceeds to step 335 wherethe new communication stream (NEW) is admitted. However, if the newcommunication stream (NEW) does not have at least one metric which isgreater than a corresponding metric of an existing communicationsupported by the node, then the method 300 proceeds to step 360, wherethe node stops processing and/or relaying packets of the newcommunication stream (NEW). In implementations where step 355 isomitted, the method 300 proceeds directly from step 350 to step 360,where admission of the new communication stream (NEW) is denied.

In one implementation of step 360, any of the nodes (destination node,or relay nodes of the new communication stream) which receive anindicator stop processing and/or relaying packets of the newcommunication stream (NEW), and drops all of outstanding packets of thenew communication stream (NEW). In one implementation, the destinationnode 138 monitors the channel for an indicator to detect QoSinfringement by the new communication stream (NEW), and if thedestination node 138 receives an indicator (during the temporaryadmission period) and notices QoS infringement, the destination node 138stops processing received data packets of the new communication stream(NEW). Similarly, the relay node 126 monitors the channel for anindicator to detect QoS infringement by the new communication stream(NEW), and if the relay node 126 receives an indicator (during thetemporary admission period) and notices QoS infringement, the relay node126 stops relaying received data packets of the new communication stream(NEW). In one implementation, the relay node stops relaying packets forall temporarily admitted new communication stream (NEW) and drops all oftheir outstanding packets.

In some scenarios, it is possible that a node is participating in thecommunication of two or more new communication streams (NEW) seekingadmission (e.g., is a relay node of 2 or more temporarily admittedcommunication streams), and the node can receive multiple differentindicators which reference to different new communication streams. Asnoted above, one approach is for the node to deny all new communicationstreams referenced by the indicator. However, in other implementations,instead of denying all temporarily admitted new communication streams,the node can deny one or more of the temporarily admitted newcommunication streams. The number of new communication streams which aredenied or “blocked” can be determined by the node based on a number ofmetrics. Thus, in some implementations, where a node is participating incommunication of two or more new communication streams (NEW) seekingadmission, the node can prioritize the new communication streams (NEW)based on one or more metrics. In other words, the node can assign apriority or order to each of the new communication streams based ontheir respective metrics. The metrics may comprise, for example, thetype of new communication stream; organization rank of a user of thesource node; organization rank of a user of the destination node;duration during which each new communication stream has been in atemporary admission period; QoS requirements of the new communicationstream, fraction of time that the channel is busy, number of packets inthe node's queue, age of the new communication stream, etc. In oneimplementation, the node can then determine a subset of the newcommunication streams (NEW) comprising: one or more lower priority, newcommunication streams (NEW) having the lowest metrics. When the nodereceives multiple indicator(s), the node can then stop processing,relaying or receiving packets associated with the one or more of thelower priority new communication streams (NEW).

At step 370, the node(s) forward the indicator(s) towards the sourcenode 124 which is generating the new communication stream (NEW). In oneimplementation of step 370, the node sends a unicast indicator (e.g.,unicast QIA message) towards the source node 124. Although notillustrated in FIG. 3, any node which receives the unicast indicator,stops processing or relaying packets of the new communication stream(NEW), drops all of its buffered packets and forwards the unicasttowards the source node 124 of the new communication stream (NEW), andwhen the source node 124 receives the indicator, the source node 124stops generating packets of the new communication stream (NEW).

In some implementations, any node that receives the indicator from anexternal route can forward the indicator to both the source node 124 anddestination node 138 and all nodes that receive this forwarded indicatorcan send their metrics (C) towards the source node 124.

When the node is the source node 124 at step 350, the method 300 canproceed to one or more of steps 380, 385, and 390, and in this regard,each of these steps is optional. In some implementations, steps 380, 385and 390 can be performed as alternatives to one another (as illustratedin FIG. 3B where either step 380 or step 385 or step 390 is performed).In other implementations, two or more of steps 380, 385 and 390 can beperformed in series and/or combination with each other (e.g., step 380,then step 390; step 380, then step 385; step 380, step 385, then step390; step 380, step 390, then step 385; step 385, then step 390 orvice-versa, etc.).

When the method 300 proceeds to step 380, where the source node 124stops generating and/or transmitting packets of the new communicationstream (NEW). For example, the source node 124 monitors the channel foran indicator to detect QoS infringement by the new communication stream(NEW), and if the source node 124 receives an indicator (during thetemporary admission period) at step 342 and notices QoS infringement,the source node 124 stops generating and transmitting data packets atstep 380. At step 382, the method 300 ends.

When the method 300 proceeds to step 385, the source node 124 determineswhether changing or altering one or more of the QoS requirements of thenew communication stream (NEW) would improve its chances or probabilityfor admission. As mentioned above, the indicator can include informationwhich indicates whether the new communication stream (NEW) would have abetter chance of admission if the overall QoS requirements of the newcommunication stream (NEW) are reduced to a lower QoS level. When thesource node 124 determines that changing or altering one or more of theQoS requirements of the new communication stream (NEW) would improve itschances or probability for admission based on information provided inone or more indicators, then the method 300 proceeds to step 387 wherethe source node 124 changes one or more of the QoS requirementsassociated with the new communication stream (NEW), and the method 300loops back to step 310. When the source node 124 determines thatchanging or altering one or more of the QoS requirements of the newcommunication stream (NEW) would not improve its chances or probabilityfor admission based on information provided in one or more indicators,then the method 300 proceeds, for example, to step 310 or 390.

When the method 300 proceeds to step 390, the source node 124 determineswhether an alternative route to the destination node 138 exists.

If so, the method proceeds to step 392, where the source node 124selects an alternative route, and then the method 300 loops back to step310 and method 300 repeats. In one implementation, the source node 124selects a new route that does not include the relay node that hasreceived an indicator from a peripheral node and does not containperipheral nodes that have generated an indicator. If such nodes wereconsidered in the alternative route, it is likely that the newcommunication stream would again infringe the QoS of existing flows. Theexclusion of such nodes will increase the likelihood that thealternative be admitted. In some implementations where the indicatorincludes a node ID of the node which initially generated the indicatorand a metric (C) as described above at step 340, to avoid the selectionof another route that would be potentially denied access, the sourcenode 124 uses the metric (C) (or the collection of metric (C)information) to aid the route selection algorithm in the selection ofthe alternative route.

If no alternative route to the destination node exists, at optional step395, the source node 124 can send a specific re-route request message orother control message to other nodes within communication range or tonodes of existing communication streams. The re-route request messagerequest that one or more of those nodes change one or more routes oftheir existing communication streams to change the topology such thatnew communication stream can be admitted without otherwise impacting ordegrading QoS requirements of the existing communication streams. If there-route request is accepted by at least one node, the source node 124may select an alternative route to node 138 or even retry the previouslydenied route.

As noted above, there are multiple different techniques for implementingstep 330 described above.

FIG. 4 is a flowchart showing one example of a method 430 fordetermining whether a new communication stream (NEW) is to be admittedor denied in accordance with some implementations of the invention. Oneor more of the steps illustrated in FIG. 4 (or any combination thereof)can be used in specific implementations of step 330 of FIG. 3. Moreover,other additional steps (not shown) can also be used in specificimplementations of step 330 of FIG. 3. One implementation of step 330includes steps 432, 436, 438 and 439. These steps are illustrated indashed line decision boxes to indicate that these steps are optional andrepresent one possible series of steps for making the determination atstep 330. Decision points 432, 436, 438 and 439 are optional and neednot be performed. In one implementation, the method 300 includes all ofsteps 432, 436, 438, 439, and in such cases, the method 300 proceedsfrom step 320 to step 432. In other implementations, any one of thesteps 436, 438, 439 or 440, or any combination of at least some of thosesteps, can be performed. Thus, in the implementation illustrated in FIG.4, there are a number of ways the new communication stream can beadmitted at step 335. One particular implementation will now bedescribed below where all of steps 432, 436, 438, and 439 are performedto decide whether the new communication stream (NEW) is to be admitted;however, one or more of these steps 432, 436, 438, and 439 can beperformed depending on the particular implementation.

In implementations where step 432 is implemented, at step 432 the nodedetermines, during the temporary admission period, whether the node canadequately support each existing communication stream supported by thatparticular node according to existing QoS requirements associated witheach of the existing communication streams which that node supports. Anode is unable to adequately support an existing communication stream ifthe particular node is no longer able to communicate that existingcommunication stream while still meeting QoS requirements of thatcommunication stream. Additionally, the node can follow thedetermination made by the source or destination nodes, which woulddetermine whether QoS requirements are being met and would provideindication on specific bits on the MAC header attached to each of thepackets of the new communication stream.

If not, then the method proceeds to step 436 of FIG. 4, where the nodedetermines whether its inability to adequately support existing QoSrequirements of existing communication streams which the node supportsis caused by the new communication stream (NEW). A node determineswhether it is unable to support the existing QoS requirements ofexisting communication streams by observing the packet error rate,packet interarrival times in the radio links and the power level inwhich packets are received. If the packets are being received withsimilar power levels as before but the packet error rate or the packetinterarrival rate has increased, it is likely due to the trafficgenerated by the new communication stream. Otherwise, if the power levelin which packets are received has reduced significantly, the QoSdegradation is likely to be due to the fact that the transmitter andreceiver of a radio link are moving farther apart from each other,making the radio link unusable.

If the node determines that the QoS degradation is not due to the newcommunication stream, then the method proceeds to step 335 of FIG. 3where the new communication stream (NEW) is admitted. For example, anynodes which determine that the new communication stream (NEW) does notcause degradation of an existing communication stream 1-4 supported bythat node can admit the new communication stream (NEW). Admission of thenew communication stream (NEW) can refer to a new or continuedtransmission of the new communication stream (NEW). This can refer to: acontinuation of the current, new communication stream; a new version ofthe current, new communication stream (i.e., starting at the beginning);or another communication stream different than the current, newcommunication stream. However, in all versions of the communicationstream, the transmission characteristics (number of packets transmittedper second and duration of packet transmission) is kept the same.

In implementations where step 436 is implemented, at step 436 the nodedetermines whether the new communication stream (NEW) has caused thenode's inability to adequately support existing QoS requirements of it'sexisting communication streams. If not, then the method proceeds to step335 of FIG. 3 where the new communication stream (NEW) is admitted. Ifso, then the method proceeds to step 438 of FIG. 4 where the nodedetermines whether the new communication stream (NEW) has at least onemetric which is greater than a corresponding metric of at least one ofit's existing communication streams. Examples of these metrics aredescribed above.

In implementations where step 438 is implemented, at step 438, the nodedetermines whether the new communication stream has at least one metricgreater than or equal to a corresponding metric of one or more of theexisting communication streams which the node supports. This allows thenode to determine whether or not the new communication stream is “betterthan” or has higher priority than one or more of the existingcommunication streams that the node supports. In one implementation, themetric can be any one of the following parameters or can be computedbased on any combination of the following parameters: type of newcommunication stream (e.g., real-time stream, non-real-time stream, besteffort stream, etc); organizational rank of user of source node 124; andorganizational rank of user of destination node 138.

If so, then the method proceeds to step 335 of FIG. 3 where the newcommunication stream (NEW) is admitted. If not, then the method proceedsto step 439 of FIG. 4 where the node determines whether the fraction oftime that the channel, which carries the new communication stream (NEW),is busy it above or below a threshold.

In implementations where step 439 is implemented, then at step 439, whenthe node determines that the fraction of time during which the channel,which carries the new communication stream (NEW), is busy is above thethreshold, then the method 300 proceeds to step 335 where the newcommunication stream (NEW) is admitted as described above, as describedabove, so that transmission of the new communication stream (NEW) oranother communication stream by the source node is permitted.

By contrast, when the node determines at step 439 that the fraction oftime that the channel is busy is at or below a threshold, then themethod proceeds to step 340 as described above.

In the foregoing specification, specific embodiments of the presentinvention have been described. However, one of ordinary skill in the artappreciates that various modifications and changes can be made withoutdeparting from the scope of the present invention as set forth in theclaims below.

Accordingly, the specification and figures are to be regarded in anillustrative rather than a restrictive sense, and all such modificationsare intended to be included within the scope of present invention. Thebenefits, advantages, solutions to problems, and any element(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeatures or elements of any or all the claims. The invention is definedsolely by the appended claims including any amendments made during thependency of this application and all equivalents of those claims asissued.

1. In a mobile ad hoc network (MANET) comprising a plurality of nodesincluding a source node, a destination node, and a plurality of firstnodes each supporting at least one existing communication stream whichhas one or more existing QoS requirements associated therewith, a methodfor distributed admission control (AC) in the mobile ad hoc network(MANET), the method comprising: transmitting, from the source node, anew communication stream toward the destination node along a first routebetween the source node and the destination node; upon receiving the newcommunication stream, allowing transmission of the new communicationstream at the plurality of nodes during a temporary admission period;determining, at each of the plurality of nodes during the temporaryadmission period, whether the new communication stream causesdegradation of at least one existing communication stream supported bythat node; and transmitting, from at least one of the plurality of nodeswhich determines that the node is unable to support existing QoSrequirements of at least one existing communication stream, an indicatorwhich indicates that the new communication stream causes degradation ofone or more existing QoS requirements associated with the at least oneexisting communication stream supported by that node
 2. A methodaccording to claim 1, further comprising: permitting transmission of thenew communication stream by the source node when one or more nodesdetermine that the new communication stream does not cause degradationof existing communication streams supported by those nodes.
 3. A methodaccording to claim 1, wherein the step of determining, at each of theplurality of nodes during the temporary admission period, whether thenew communication stream causes degradation of at least one existingcommunication stream supported by that node, comprises: determining, ateach of the plurality of nodes during the temporary admission period,whether that node is able to support each existing communication streamsupported by that node according to existing QoS requirements associatedwith each existing communication stream; and determining, at each of theplurality of nodes which determine that the node is unable to supportone or more existing communication streams according to existing QoSrequirements associated with the existing communication stream, whetherthe degradation of the at least one existing communication streamsupported by that node is caused by the new communication stream.
 4. Amethod according to claim 3, further comprising: determining, uponreceiving the new communication stream, whether the new communicationstream has at least one metric higher than a metric of any of theexisting communication streams that the node is supporting; andadmitting the new communication stream at the node when the nodedetermines that the new communication stream has at least one metrichigher than a metric of any existing communication streams that the nodeis supporting such that continued transmission of the new communicationstream from the source node is permitted by the node.
 5. A methodaccording to claim 4, further comprising: determining, at a node,whether a fraction of time that a channel is busy is below a threshold;and suppressing transmission of an indicator at the node if the fractionof time that the channel is busy is below the threshold.
 6. A methodaccording to claim 4, further comprising: determining, at a node,whether the packet transmission rates of neighbor nodes have notincreased by more than a particular percentage; and suppressingtransmission of an indicator at the node if the packet transmissionrates of the neighbor nodes have not increased by more than theparticular percentage.
 7. A method according to claim 1, furthercomprising: receiving, at one or more of the nodes, at least oneindicator, wherein the indicator further comprises: information whichindicates that the new communication stream (NEW) would have a betterchance of admission by the node transmitting the indicator if theoverall QoS requirements of the new communication stream (NEW) arechanged by the source node; and further comprising at least one step of:forwarding the at least one indicator, from the nodes which receive theat least one indicator, towards the source node which generates the newcommunication stream so that the source node stops generating packets ofthe new communication stream; stopping, at the source node uponreceiving the at least one indicator, generation of packets of the newcommunication stream; and determining, at the source node upon receivingthe at least one indicator, whether changing one or more of the QoSrequirements of the new communication stream will increase chances ofadmission of the new communication stream along the route.
 8. A methodaccording to claim 1, further comprising: determining, at the sourcenode, determines whether there one or more alternative routes to thedestination node exists; selecting, at the source node, one of thealternative routes to the destination node using a selection criteria,wherein the selection criteria are designed to decrease the probabilityof selection of routes which: include one or more relay nodes that havereceived an indicator from a peripheral node, or include peripheralnodes that have generated an indicator; and transmitting, from thesource node, a re-route request message to other nodes if no alternativeroutes to the destination node exist, wherein the re-route requestmessage request that one or more nodes change one or more routes oftheir existing communication streams to change the topology such thatnew communication stream can be admitted without degrading QoSrequirements of the existing communication streams.
 9. A methodaccording to claim 1, further comprising: receiving, at one or more ofthe nodes, at least one indicator; and stopping, at the nodes whichreceive the at least one indicator, processing of packets of the newcommunication stream.
 10. A method according to claim 1, wherein theplurality of nodes further include: one or more relay nodes along thefirst route between the source node and the destination node, andwherein the new communication stream is communicated towards thedestination node by the one or more relay nodes, and further comprising:receiving, at one or more of the nodes, at least one indicator; andstopping, at the relay nodes which receive the at least one indicator,relaying of packets of the new communication stream.
 11. A methodaccording to claim 1, wherein the new communication stream comprises:one or more dummy packets which are transmitted using a same packet sizeand a same packet inter-arrival time as regular packets of the newcommunication stream during the temporary admission period.
 12. A methodaccording to claim 1, wherein the step of transmitting an indicator,comprises: transmitting, from one of the nodes which determines that thenode is unable to support existing QoS requirements of at least oneexisting communication stream, a unicast QoS Infringement Alert (QIA)message to a neighbor node which has a highest increase of packettransmission rate during a measurement period.
 13. A method according toclaim 1, wherein a node participates in communicating two newcommunication streams, and further comprising: assigning a priority toeach of the two new communication streams based on at least one metricassociated with each of the two new communication streams; receiving, atthe node, at least one indicator; and stopping, at the node uponreceiving the at least one indicator, processing of packet associatedwith the new communication stream having a lower priority.
 14. In amobile ad hoc network (MANET) a plurality of nodes, comprising: adestination node; a source node designed to transmit a new communicationstream toward the destination node along a first route between thesource node and the destination node; and a plurality of first nodeseach supporting at least one existing communication stream which has oneor more existing QoS requirements associated therewith; wherein each ofthe nodes are designed to allow, upon receiving the new communicationstream, continued transmission of the new communication stream during atemporary admission period, and to determine whether the newcommunication stream causes degradation of at least one existingcommunication stream supported by that node, and wherein each of thenodes which are unable to support existing QoS requirements of at leastone existing communication stream supported by that node are designed totransmit an indicator which indicates that the new communication streamcauses degradation of the at least one existing communication streamsupported by that node.
 15. A mobile ad hoc network (MANET) according toclaim 14, wherein: one or more nodes, which determine that the newcommunication stream does not cause degradation of existingcommunication streams supported by those nodes, are designed to permitcontinued transmission of the new communication stream by the sourcenode after the temporary admission period.
 16. A mobile ad hoc network(MANET) according to claim 14, wherein each node is further designed todetermine, during the temporary admission period, whether that node isable to support each existing communication stream supported by thatnode according to existing QoS requirements associated with eachexisting communication stream, and wherein each node, which determinesthat the node is unable to support one or more existing communicationstreams according to existing QoS requirements associated with eachexisting communication stream of the node, is designed to determinewhether the degradation of the at least one existing communicationstream supported by that node is caused by the new communication stream.17. A mobile ad hoc network (MANET) according to claim 16, wherein eachnode is further designed to: determine, upon receiving the newcommunication stream, whether the new communication stream has at leastone metric higher than a metric of any of the existing communicationstreams that the node is supporting; and admit the new communicationstream at the node when the node determines that the new communicationstream has at least one metric higher than a metric of any existingcommunication streams that the node is supporting such that continuedtransmission of the new communication stream from the source node ispermitted by the node.
 18. A mobile ad hoc network (MANET) according toclaim 17, wherein each node is further designed to determine whether atleast one of: a fraction of time that a channel is busy is below athreshold, and packet transmission rates of neighbor nodes have notincreased by more than a particular percentage; and wherein the node isdesigned to suppress transmission of the indicator if at least one of:the fraction of time that the channel is busy is below the threshold;and the packet transmission rates of the neighbor nodes have notincreased by more than the particular percentage.
 19. A mobile ad hocnetwork (MANET) according to claim 14, wherein each node is furtherdesigned to: receive at least one indicator, wherein the indicatorfurther comprises: information which indicates that the newcommunication stream (NEW) would have a better chance of admission bythe node transmitting the indicator if the overall QoS requirements ofthe new communication stream (NEW) are changed by the source node; andwherein each node which receives the at least one indicator is furtherdesigned to: forward the at least one indicator towards the source nodewhich generates the new communication stream so that the source nodestops generating packets of the new communication stream; wherein thesource node is further designed to, upon receiving the at least oneindicator, stop generating packets of the new communication stream, anddetermine whether changing one or more of the QoS requirements of thenew communication stream will allow admission of the new communicationstream along the route.
 20. A mobile ad hoc network (MANET) according toclaim 14, wherein each node is further designed to: stop processing ofpackets of the new communication stream upon receiving the at least oneindicator.
 21. A mobile ad hoc network (MANET) according to claim 12,wherein the plurality of nodes further include: one or more relay nodesalong the first route between the source node and the destination node,and wherein the new communication stream is communicated towards thedestination node by the one or more relay nodes, and wherein the relaynodes which receive the at least one indicator are further designed tostop relaying of packets of the new communication stream.
 22. A nodedesigned to communicate in a mobile ad hoc network (MANET) comprising aplurality of nodes comprising a source node designed to transmit a newcommunication stream in a first route, wherein the node supports anexisting communication stream which has one or more existing QoSrequirements associated therewith, and wherein the node is designed toallow, upon receiving the new communication stream, continuedtransmission of the new communication stream during a temporaryadmission period, the node comprising: a processor designed to determinewhether the new communication stream causes degradation of the existingcommunication stream supported by that node, and a transmitter designedto transmit an indicator which indicates that the new communicationstream causes degradation of the at least one existing communicationstream supported by that node when the node determines that the newcommunication stream causes degradation of the existing communicationstream.